A Walk-Through of AGN Country -- for the somewhat initiated!

TL;DR

This paper reviews key issues in AGN and galaxy formation, emphasizing the unified models, AGN feedback phenomena like the alignment effect, and debunking the thin accretion disk model, offering new insights into nuclear dust and emission.

Contribution

It provides a comprehensive review of AGN models, introduces a robust derivation of dust reddening law, and challenges the thin accretion disk paradigm with new arguments.

Findings

The alignment effect is a key AGN feedback phenomenon.

High nuclear dust polarization is observed only in radio loud objects.

The thin accretion disk model is thoroughly debunked.

Abstract

Some key issues in AGN and galaxy formation are discussed. Very successful Unified Models explain much of the variety of AGN with orientation effects; ingredients are shadowing by a dusty "torus" and relativistic beaming. A spinoff result is described which is important for the formation of massive elliptical galaxies. It's the most spectacular and unequivocal AGN feedback phenomenon known. This is the so-called "alignment effect" in powerful radio galaxies at z>~1. One of them is a BAL radio galaxy! I explain a very robust derivation of the reddening law for nuclear dust, which reveals a dearth of small grains. Then the quasistatic thin accretion disk model, thought by many to explain the energetically dominant optical/UV continuum, is thoroughly debunked. Much of this was known when the model was proposed 35 years ago. A new argument is given that trivially falsifies a huge superset of such models. It's possible to see the central engine spectrum with the atomic and dust emission surgically removed! Few noticed this breakthrough work. The far IR dust emission in Cygnus A is 10% polarized, and so far high nuclear dust polarization is seen in all radio loud objects, but no radio quiet ones.